1. Field of the Invention
This invention relates to magnetic tape recording apparatus, and more particularly, to a battery operated load survey recorder for providing a magnetic tape recording of data relating to measurement data along with a time reference on separate tracks of a magnetic tape.
2. Description of the Prior Art
Load survey recorders are employed by the utility industry for automatically providing information relating to usage of a commodity, such as gas, water, or electricity, by a consumer. Typically, load survey recorders are used to provide a data record which is of assistance for the utility company in its evaluation of the load conditions for different types of customers, automatic billing, and the like.
One known load survey recorder for recording data relating to the load measured by a utility meter is disclosed in the U.S. Pat. No. 3,829,772 of N. F. Marsh, G. W. Morand and D. G. Sokol, entitled "LOAD SURVEY RECORDER FOR MEASURING ELECTRICAL PARAMETERS," which issued on Aug. 13, 1974. The survey recorder basically comprises a two-track cassette recorder including recorder circuitry which records data on a first track of the tape and timing pulses on a second track of the tape for identifying predetermined time intervals in which data recording occurs. Both data and time information are recorded in an NRZ1 (non-return to zero) format, with changes in polarity occuring on the data track being effected in response to the data pulses supplied to a first section of the recording circuitry, and changes in the polarity on the time track occuring in response to timing pulses supplied to a second section of the recording circuitry. The survey recorder employs a cassette tape cartridge which is changed at predetermined intervals, which in certain commercial applications is on the order of 30- 35 days, and played back over tape processing equipment having a conventional playback head for the purpose of retrieving the recorded information.
While the survey recorder disclosed in the patent referenced above provides a magnetic recording of data with a time reference in a form which is compatible for use with available data processing equipment, the recorder requires 120 VAC power for energization. In some applications, 120 VAC is either not available or it is not desired. Accordingly, it would be desirable to have a battery operated load survey recorder which provides reliable recording of both data and a time reference on magnetic recording tape and which does not require commercial electrical power. It would also be desirable to have a battery operated load survey recorder which minimizes current drain on the battery such that the battery life is comparable with the cassette change interval.